How to Apply Polyurethane to an Old Oak Tabletop

Oil-based polyurethane is easier to apply than water-based.

Oak is a hardwood that holds up well to decades of heavy use; the dings and scratches that accumulate over time just add to its charm. A polyurethane finish protects and enhances an oak tabletop’s surface while allowing its charm to shine through.

Types of Polyurethane

Oil-based polyurethane is easiest to apply and requires fewer coats, but it leaves a thick finish that takes a long time to cure. Water-based polyurethane is harder to apply without leaving brush marks. It also requires more coats and heavier sanding between coats because it raises the wood’s grain. Tung oil -- oil-based polyurethane mixed with paint thinner -- requires many coats but has a thin, more natural-looking finish.

Surface Preparation

Sand the tabletop. Start with 100-grit paper and work your way up to 220. Vacuum or brush the sawdust off the table, then wipe the surface with a cloth dampened with denatured alcohol. Wipe the wood with a tack cloth to remove any last bits of dust.

Applying Polyurethane

Brush thin coats of polyurethane with the grain, using a foam brush. Work side to side, then front to back in small sections. Keep wet edges. As you move from one section to the next, work the polyurethane into the previous section’s edges to avoid lines and brush marks. Cure the finish until it’s completely dry, then lightly sand the surface with 220-grit sandpaper. Remove the dust with a tack cloth before applying the next coat. Continue these steps until you achieve the desired finish.

About the Author

Daria Kelly Uhlig began writing professionally for websites in 2008. She is a licensed real-estate agent who specializes in resort real estate rentals in Ocean City, Md. Her real estate, business and finance articles have appeared on a number of sites, including Motley Fool, The Nest and more. Uhlig holds an associate degree in communications from Centenary College.